Lymphocytic lymphoma with associated gamma heavy chain and IgM-lambda paraproteins. An unusual biclonal gammopathy.

Evaluation of proteinuria in a 66-year-old white female detected the presence of two distinct anomalous proteins: a gamma heavy chain devoid of light chains and an intact IgM-lambda paraprotein. The gamma heavy chain protein was incomplete, antigenically corresponding to the Fc portion of the molecule. Subsequent diagnostic studies of the patient revealed the simultaneous presence of an adenocarcinoma of the colon and an extranodal well-differentiated lymphocytic lymphoma involving the lungs, pulmonary hilum, and upper gastrointestinal tract. Levels of the two paraproteins were unaltered by surgical excision of the colonic carcinoma but were reduced by chemotherapy directed at the lymphoma.